(1) Field of the Invention
The present invention relates to a colored coating composition and colored films which are obtained by using the composition in vacuum forming.
(2) Description of the Prior Art
In recent years, a method of applying a colored film by vacuum forming onto a member such as automobile parts in place of a method of coating a colored coating composition directly onto the member is being used because the former method has such advantages over the latter because the former method makes it possible to form a colored layer which has a uniform film thickness even on members with complicated shapes, and also makes it possible to easily carry out the printing of patterns, etc.
The above vacuum forming may be carried out, for example, as shown in FIGS. 1 and 2, by a process which comprises placing a colored film (2) for use in vacuum forming onto an upper face of a vacuum forming apparatus (6) provided with a heater (1) and a rest (4), followed by heating the colored film (2) at temperatures usually in the range of 100.degree. C. to 150.degree. C. by use of the heater (1) to be softened, and sucking a gas within the vacuum forming apparatus so that the colored film (2) may be adhered onto the surface of a member (3) to cover it.
The has been used in the art a colored film which was obtained by forming an adhesive layer on one side of a base film such as polyurethane film, polyester film or the like and by forming an acrylic polyol/polyisocyanate based metallic coating film layer on the other side of the base film.
However, the above colored film has disadvantages such as the heating of the base film at such temperatures as to make possible the vacuum forming reduces the elongation of the metallic coating film which results in causing coating film defects such as crazing, cracking and peeling on the metallic coating film after the vacuum forming.
Furthermore, it is necessary for the metallic layer as the colored layer and a clear layer to cover the metallic layer to have about double the film thickness of the normal coating film in order to obtain a satisfactory elongation of the metallic coating film after fabrication. The application of the spray coating process for increasing the film thickness of the metallic layer and the clear layer as above mentioned uses a large amount of thinner which results in such disadvantages as that the base film is impregnated with thinner and foaming takes place within the base film, the colored layer, the clear layer and the like during the vacuum forming.